The invention relates to video display systems and particularly to video display systems requiring high resolution of detail in the displayed image.
The invention is directed to the need to extract small features from large surface areas using video technology. The primary problem inherent in the prior art is that analog data sources such as maps, photographs and x-rays present thousands of lines (or points per line) of information per inch of surface over many square inches of surface area. A single frame of common video can resolve fewer than a thousand lines (or points pef line). Typical video resolution is about five hundred lines (or points per line) for common video products on the market today.
The solution to this problem, represented by the present invention, involves understanding "format size" as a function separate from "resolution". "Resolution" describes a specification as to the number of resolvable points of information available per unit of distance or area relative to the material used to produce the image (map, x-ray or the like) or to scan the subject being imaged (film, video camera, and the like). It can be described in familiar terms as the "grain of the film" or the "line resolution quality" based on some standard image pattern exposed through a standard "format size" film or camera sensory plate. "Format size" refers to a unit of distance or area describing the actual physical size of the film plate employed or the camera sensory plate.
For example, if it is necessary to capture one thousand points of information per line, one could use a piece of film which had a one thousand line per inch resolution with a small format size of one inch or one could use a piece of film with a five hundred line per inch resolution and a two inch format size.
Where the problem becomes most evident is in the case of video which exists most commonly in the (approximately) sixteen millimeter format size with a maximum resolution, most commonly, of only about five hundred lines. Video camera format sizes are typically related to the diameter of the target (camera sensory plate) housing. The most common sizes are two-thirds inch and one inch. Either size is used with optics and designs of a mechanical and electronic nature to produce the equivalent performance of approximately sixteen millimeter film format size.